Surgical instrument and methods of use thereof

ABSTRACT

A surgical instrument includes a housing, an outer shaft, an inner shaft, a trial sizer, a rod, and a head. The outer shaft is operatively coupled with the housing such that rotation of the housing causes axial displacement of the outer shaft. The outer shaft includes a keel cutter configured to form a channel in a vertebral body. The inner shaft disposed within the outer shaft. The trial sizer is configured to be received in intervertebral space. The trial sizer includes a pair of wings transitionable between a retracted position and an extended position in which the pair of wings extends transversely outward. The head is connected to the rod, wherein the head is operatively coupled with the pair of wings such that axial displacement of the rod causes transition of the pair of wings between the retracted and extended positions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to, and the benefit of, U.S.Provisional Patent Application Ser. No. 62/280,206, filed on Jan. 19,2016, the entire contents of which are incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to an instrument for spinal surgery and,more particularly, to surgical instruments and methods for forming akeel channel in vertebral bodies.

2. Discussion of Related Art

Surgical procedures are performed to correct problems with displaced,damaged, or degenerated intervertebral discs due to trauma, disease, oraging. One of the most common procedures is spinal fusion. However,total disc replacement procedures are being utilized as an alternativeto spinal fusion. The replacement procedure involves implantation ofdevices designed to replace the functions of the intervertebral disc andthus preserve motion that is lost through a spinal fusion.

The implant generally has an implant body and a keel structure, whichcan augment anti-migration features of the implant and further stabilizethe position of the implant within the intervertebral space. Keelstructures may extend above the upper surface and/or below the lowersurface. Keel structures may be canted or generally perpendicular to thesurface from which they extend. During implantation the keel structurescan be inserted into keel channels formed in the adjacent vertebrae.Apertures may be provided along the length of the keel, or a portionthereof, to permit bony ingrowth through the keel structures.

Current surgical procedures utilize a trial sizer instrument and aseparate keel cutter. The trial sizer may be inserted into theintervertebral space to determine the size of an appropriate implantrequired to achieve the desired disc height. The keel cutter is thenadvanced into the intervertebral space to form channels in the vertebralbodies for receiving the keel structures that are present on theimplant.

Therefore, a continuing need exists for an improved device and a methodfor determining a desired implant size and forming a keel channel thatcan minimize the number of instruments, steps, and time involved in asurgical procedure.

SUMMARY

In accordance with an embodiment of the present disclosure, a surgicalinstrument includes a housing, an outer shaft, an inner shaft, a trialsizer, a rod, and a head. The outer shaft is operatively coupled withthe housing such that rotation of the housing causes axial displacementof the outer shaft. The outer shaft includes a keel cutter configured todefine a channel in a vertebral body. The inner shaft is disposed withinthe outer shaft. The trial sizer is configured to be received inintervertebral space. The trial sizer includes a pair of wingstransitionable between a retracted position and an extended position inwhich the pair of wings extends transversely outward. The head isconnected to the rod, wherein the head is operatively coupled with thepair of wings such that axial displacement of the rod causes transitionof the pair of wings between the retracted and extended positions.

In an embodiment, the outer shaft may include a pair of keel cutters.

In another embodiment, the head may include grooves and each groovesdefines an acute angle with respect to a longitudinal axis of the rod.Each of the wings may include a guide configured to be received in therespective groove of the head.

In yet another embodiment, the trial sizer may include pins and definebores dimensioned to receive the respective pins. In particular, each ofthe wings may define a lateral slot configured to slidably receive oneof the pins.

In yet another embodiment, the keel cutter may be transitionable betweenan extended position and a retracted position, wherein the keel cutterextends over the trial sizer when the keel cutter is in the extendedposition.

In still yet another embodiment, the surgical instrument may furtherinclude a wheel operatively coupled with the rod. Rotation of the wheelmay cause axial displacement of the rod.

In still yet another embodiment, the housing is rotatable about theouter shaft.

In an embodiment, the trial sizer may have a width ranging from about 14mm to about 20 mm. Alternatively, the trial sizer may have a widthranging from about 18 mm to about 30 mm.

In still yet another embodiment, the head may be tapered.

In still yet another embodiment, the outer shaft may have a plurality ofopenings.

In still another embodiment, a distal-most end of the keel cutter may betapered. The keel cutter may extend along a longitudinal axis of theouter shaft. The keel cutter may be centered between the wings.

In accordance with another aspect of the present disclosure, a method offorming a keel channel in a vertebral body is disclosed. The methodincludes inserting a trial sizer of a keel cutting instrument into anintervertebral space and transitioning a pair of wings of the trialsizer from a retracted position to an extended position. The pair ofwings extends transversely outward in the extended position. The methodalso includes translating a keel cutter of the keel cutting instrumentinto a vertebral body to form a keel channel and removing the keelcutting instrument from the intervertebral space. The method includesplacing an implant into the intervertebral space.

In an embodiment, transitioning the pair of wings of the trial sizer mayinclude centering the trial sizer within the intervertebral space.

In another embodiment, the method may further include placing the keelcutter against a vertebral body prior to translating the keel cutter.

In yet another embodiment, translating the keel cutter may includerotating a housing of the keel cutting instrument. The housing beingrotatably coupled with an outer shaft of the keel cutting instrumentsuch that the keel cutter disposed on the outer shaft extends over thetrial sizer.

In still yet another embodiment, placing the implant in theintervertebral space may include positioning a keel structure of theimplant into the keel channel defined in the vertebral body.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the present disclosure are described hereinbelow withreference to the drawings, wherein:

FIG. 1A is a perspective view of a keel cutter instrument in accordancewith an embodiment of the present disclosure;

FIG. 1B is a partially enlarged perspective view of a distal portion ofthe keel cutter instrument of FIG. 1A;

FIG. 1C is a partially enlarged side view of the distal portion of thekeel cutter instrument of FIG. 1B;

FIG. 1D is a partially enlarged cross-sectional view of a proximalportion of the keel cutter instrument of FIG. 1A;

FIG. 2A is a perspective view of the keel cutter instrument of FIG. 1Aillustrating a pair of wings in an extended state;

FIG. 2B is a partially enlarged perspective view of the keel cutterinstrument of FIG. 2A illustrating the pair of wings in the extendedstate;

FIG. 2C is an exploded perspective view of the keel cutter instrument ofFIG. 2B with parts separated;

FIG. 3A is a perspective view of the keel cutter instrument of FIG. 1A;

FIG. 3B is a partially enlarged perspective view of the keel cutterinstrument of FIG. 3A illustrating the keel cutter in the extendedstate;

FIG. 3C is a partially enlarged side view of the keel cutter instrumentof FIG. 3B;

FIGS. 4A-5C are perspective views of the keel cutter instrument of FIG.1A illustrating use thereof;

FIG. 6 is a perspective view of a keel cutter instrument in accordancewith another embodiment of the present disclosure;

FIG. 7 is a side view of the keel cutter instrument of FIG. 6;

FIG. 8 is a top view of the keel cutter instrument of FIG. 8;

FIG. 9 is an exploded perspective view of the keel cutter instrument ofFIG. 6 with parts separated;

FIGS. 10 and 11 are partially enlarged top views of the keel cutterinstrument of FIG. 6;

FIG. 12 is a partially enlarged side view of the keel cutter instrumentof FIG. 6;

FIG. 13 is a perspective view of a keel cutter instrument in accordancewith another embodiment of the present disclosure;

FIG. 14 is a side cross-sectional view of the keel cutter instrument ofFIG. 13;

FIG. 15 is a perspective view of an outer assembly of the keel cutterinstrument of FIG. 13;

FIG. 16 is an exploded perspective view of the outer assembly of FIG. 15with parts separated;

FIG. 17 is a perspective view of an inner assembly of the keel cutterinstrument of FIG. 13;

FIG. 17A is an exploded perspective view of the inner assembly of FIG.17 with parts separated;

FIG. 18 is a top cross-sectional view of the inner assembly of FIG. 17;

FIG. 19 is a side view of the inner assembly of FIG. 17;

FIG. 20 is a top view of the inner assembly of FIG. 17; and

FIG. 21 is a partially enlarged perspective view of the keel cutterinstrument of FIG. 13.

DETAILED DESCRIPTION

Embodiments of the present disclosure are now described in detail withreference to the drawings in which like reference numerals designateidentical or corresponding elements in each of the several views. Asused herein, the term “clinician” refers to a doctor, a nurse, or anyother care provider and may include support personnel. Throughout thisdescription, the term “proximal” will refer to the portion of the deviceor component thereof that is closest to the clinician and the term“distal” will refer to the portion of the device or component thereofthat is farthest from the clinician. In addition, the term “cephalad” isused in this application to indicate a direction toward a patient'shead, whereas the term “caudad” indicates a direction toward thepatient's feet. Further still, for the purposes of this application, theterm “lateral” indicates a direction toward a side of the body of thepatient, i.e., away from the middle of the body of the patient. The term“posterior” indicates a direction toward the patient's back, and theterm “anterior” indicates a direction toward the patient's front.Additionally, in the drawings and in the description that follows, termssuch as front, rear, upper, lower, top, bottom, and similar directionalterms are used simply for convenience of description and are notintended to limit the disclosure.

With reference to FIGS. 1A and 1B, a keel cutter instrument inaccordance with an embodiment of the present disclosure is generallyshown as a keel cutter instrument 10. Keel cutter instrument 10 may beutilized to define a properly aligned keel channel or channel in avertebral body for receiving a keel structure of an intervertebralimplant. In particular, keel cutter instrument 10 enables formation of akeel channel in a vertebral body, while ensuring proper placement ofkeel cutter instrument 10 within an intervertebral space such that thechannel may be, e.g., centered, in the vertebral body. Keel cutterinstrument 10 includes an outer shaft 20, a housing 16 rotatably coupledwith outer shaft 20, and a keel cutter 22 coupled with the outer shaft20. Rotation of housing 16 causes axial displacement of keel cutter 22,as will be discussed hereinbelow. Keel cutter instrument 10 furtherincludes an inner shaft 28 at least partially disposed within outershaft 20 and a trial sizer 24 connected to inner shaft 28. Trial sizer24 includes a pair of wings 26 a, 26 b transitionable between aretracted state (FIG. 1B) and a deployed state (FIG. 2B) to enableproper placement of trial sizer 24 in the intervertebral space, as willbe described hereinbelow.

With reference to FIGS. 1B-1D, outer shaft 20 is dimensioned to beslidably disposed on inner shaft 28. Housing 16 is threadably coupledwith outer shaft 20 such that rotation of housing 16 causes axialdisplacement of outer shaft 20, which, in turn, causes axialdisplacement of keel cutters 22 a, 22 b. Keel cutter instrument 10discloses a pair of keel cutters 22 a, 22 b disposed on opposite sidesof outer shaft 20. However, it is envisioned that a single keel cuttermay be utilized. Outer shaft 20 may define a plurality of openings 18 tofacilitate sterilization of keel cutter instrument 10.

With continued reference to FIGS. 1B-1D, at least a portion of innershaft 28 extends through a cover 14. Cover 14 is stationary and providesa gripping surface for the clinician. Inner shaft 28 is coupled withtrial sizer 24. The shape and size of trial sizer 24 may be tailored tothe particular surgical procedure being performed.

With reference to FIGS. 2A-2C, trial sizer 24 includes wings 26 a, 26 btransitionable between a retracted state (FIG. 1B) and a deployed state(FIG. 2B). Keel cutter instrument 10 further includes a wheel 12 and arod 38 (FIG. 2C). Rod 38 is rotatably coupled with wheel 12 such thatrotation of wheel causes axial displacement of rod 38. Rod 38 isslidably disposed within inner shaft 28. Rod 38 operatively connectswheel 12 with head 42 disposed at a distal end 38 a of rod 38. Head 42is tapered along a longitudinal axis “X-X” defined by rod 38. Head 42defines a pair of grooves 36 defining an acute angle with respect tolongitudinal axis “X-X”.

With continued reference to FIGS. 2A-2C, the pair of wings 26 a, 26 bmay increase the width of the trial sizer 24 by, e.g., about 4 mm, whentransitioned from the retracted state to the deployed state.Transitioning of the pair of wings 26 a, 26 b from the retracted stateto the deployed state enables proper placement of trial sizer 24 withinthe intervertebral space. In this manner, trial sizer 24 may be properlycentered in the intervertebral space. For example, the pair of wings 26a, 26 b may engage the uncinated process of a cervical vertebra when thepair of wings 26 a, 26 b is in the deployed states to effect centeringof trial sizer 24. In this manner, centering trial sizer 24 within theintervertebral space enables proper placement of the channel formed bykeel cutters 22 a, 22 b in a vertebral body.

With particular reference to FIG. 2C, trial sizer 24 defines holes 40 a,40 b dimensioned to receive respective pins 30 a, 30 b. Each wing 26 a,26 b defines a respective transverse slot 32 a, 32 b configured toreceive respective pin 30 a, 30 b. In addition, each wing 26 a, 26 bincludes a projection 34 defining an acute angle with respect tolongitudinal axis “X-X.” Projections 34 are configured to be slidablyreceived in respective grooves 36 defined in head 42. Axial displacementof rod 38 causes transition of the pair of wings 26 a, 26 b between theretracted and deployed states. Accordingly, rotation of wheel 12 in afirst direction causes axial displacement of rod 38 in a distaldirection. Such movement causes projections 34 on the pair of wings 26a, 26 b to slide within respective grooves 36 defined in head 42 suchthat the pair of wings 26 a, 26 b transitions to the deployed state(FIGS. 2A and 2B). When the user rotates wheel 12 in a second directionopposite of the first direction, the pair of wings 26 a, 26 btransitions to the retracted position (FIGS. 1A and 1B).

With reference now to FIGS. 3A-3C, keel cutters 22 a, 22 b extend alonglongitudinal axis “X-X” (FIG. 2C). Keel cutters 22 a, 22 b may betapered to facilitate insertion into bone. Keel cutters 22 a, 22 b maybe centered with respect to trial sizer 24. Keel cutters 22 a, 22 b maybe moved distally to define keel channels in a vertebral body.Specifically, the clinician may rotate housing 16 in a first direction,which, in turn, causes axial displacement of outer shaft 20 in a distaldirection. In this manner, each of keel cutters 22 a, 22 b forms achannel in a vertebral body while keel cutters 22 a, 22 b extend overtrial sizer 24 (FIGS. 3B and 3C). However, when the clinician rotateshousing 16 in a second direction opposite of the first direction, keelcutters 22 a, 22 b move proximally (FIG. 1B). Combining a keel cutterinstrument with a trial sizer instrument simplifies the procedure byallowing the clinician to determine the size of the implant andsimultaneously prepare the disc space for inserting the implant, whileensuring proper placement of the trial sizer within the intervertebralspace such that proper, e.g., centered, formation of a keel channel in avertebral body is effected.

With reference to FIGS. 4A-5C, in use, the clinician initially preparesthe intervertebral space. Trial sizer 24 is inserted into the preparedintervertebral space (FIG. 4A). At this time, wheel 12 is rotated totransition the pair of wings 26 a, 26 b to the deployed state (FIG. 4B).In this manner, trial sizer 24 may be properly centered within theintervertebral space. At this time, keel cutters 22 a, 22 b may be flushagainst or abut a vertebral body. The clinician may rotate housing 16,which, in turn, moves keel cutters 22 a, 22 b distally over trial sizer24 (FIG. 5B), thereby forming the desired keel channels in the vertebralbodies (FIG. 5C). Optionally, wheel 12 can be rotated in an oppositedirection so that the pair of wings 26 a, 26 b can be transitioned tothe retracted state. Upon formation of the channels, keel cutterinstrument 10 may be removed from the surgical site. Thereafter animplant (not shown) may be inserted into the intervertebral space suchthat a keel structure of the implant is received in at least one of thekeel channels formed by keel cutters 22 a, 22 b.

Trial sizer 24 in the retracted state may have a width ranging fromabout 14 mm to about 20 mm. For example, trial sizer 24 may have a widthof about 16 mm. Trial sizer 24 may have a width of about 18 mm when usedfor cervical implants. The width may range from about 18 mm to about 30mm such as, e.g., 22 mm. For example, the width may be about 26 mm whenused for lumbar implants.

It is contemplated that a keel cutter instrument kit for use withcervical implants may include a plurality of keel cutter instruments 10having different dimensions. For example, the kit may include a firstkeel cutter instrument 10 including a trial sizer 24 having a width ofabout 14 mm, a second keel cutter instrument 10 having a trial sizer 24having a width of about 16 mm, a third keel cutter instrument 10 havinga trial sizer 24 with a width of about 18 mm, and a fourth keel cutterinstrument 10 having a trial sizer 24 with a width of about 20 mm.

It is further contemplated that a keel cutter instrument kit for usewith lumbar implants may include a first keel cutter instrument 10including a trial sizer 24 having a width of about 18 mm, a second keelcutter instrument 10 having a trial sizer 24 having a width of about 22mm, a third keel cutter instrument 10 having a trial sizer 26 with awidth of about 18 mm, and a fourth keel cutter instrument 10 having atrial sizer 24 with a width of about 30 mm.

With reference now to FIGS. 6 and 9, there is provided a keel cutterinstrument 100 in accordance with another embodiment of the presentdisclosure. Keel cutter instrument 100 includes an outer assembly 150and an inner assembly 180. Outer assembly 150 includes a handle 152, anelongate member 154 extending from handle 152, a rotatable sleeve 156,and an outer member 160 having a keel cutter 162. Outer member 160 isoperatively coupled with rotatable sleeve 156 such that rotation ofrotatable sleeve 156 causes axial displacement of outer member 160.Elongate member 154 includes a trial sizer 124 including a pair of wings126 a, 126 b transitionable between a retracted position and a deployedposition to provide proper placement of trial sizer 124 within anintervertebral space, as described hereinabove with respect to keelcutter instrument 10.

Inner assembly 180 includes an inner member 183 operatively coupled withthe pair of wings 126 a, 126 b such that axial displacement of innermember 183 transitions the pair of wings 126 a, 126 b between theretracted and deployed positions. Inner member 183 is slidably receivedthrough elongate member 152. In addition, inner assembly 180 furtherincludes a coupling member 182 threadably coupled with handle 152. Awheel 112 is rotatably coupled with coupling member 182 and inner member183 such that rotation of wheel 112 causes axial displacement of innermember 183, which, in turn, causes transition of the pair of wings 126a, 126 b between the retracted and deployed positions.

With reference now to FIGS. 7 and 8, coupling member 182 may beselectively engaged with handle 152 to determine an angular orientationof the pair of wings 126 a, 126 b when in the deployed position. Forexample, by shortening the distance between wheel 112 and handle 152through rotation of coupling member 182, the pair of wings 126 a, 126 bmay provide a greater angle between the pair of wings 126 a, 126 b whenin the deployed position. When wheel 112 is rotated, the pair of wings126 a, 126 b transition between the retracted and deployed positions.The method of use of keel cutter instrument 100 is substantiallyidentical to the method described hereinabove with respect to keelcutter instrument 10, and thus will not be described herein.

With reference now to FIGS. 13 and 14, there is provided a keel cutterinstrument 200 in accordance with another embodiment of the presentdisclosure. Keel cutter instrument 200 includes an outer assembly 250and an inner assembly 280. With reference to FIGS. 15 and 16, outerassembly 250 includes a handle 252, an elongate member 254 extendingfrom handle 252, a rotatable sleeve 256, and an outer member 260including a pusher 257. Outer member 260 is operatively coupled withrotatable sleeve 256 such that rotation of rotatable sleeve 256 causesaxial displacement of outer member 260. Elongate member 254 includes atrial sizer 224 configured to be received in the intervertebral space.

With reference now to FIGS. 17-20, inner assembly 280 includes an innermember 283 including keel cutter 262. Inner member 283 is slidablyreceived through elongate member 254 (FIG. 15). In addition, innerassembly 280 further includes a coupling member 282 threadably coupledwith handle 252.

Keel cutter 262 is movable relative to inner member 283. Wheel 212 maybe selectively engaged with coupling member 282 to define the axialdistance such as, e.g., a maximum distance of travel, of keel cutter262. For example, by increasing the distance between wheel 212 andcoupling member 282 through rotation of wheel 212, the distance that canbe traveled by keel cutter 262 through rotation of rotatable sleeve 256may be reduced. As discussed hereinabove, rotation of sleeve 256 causesaxial displacement of pusher 257, which, in turn, moves keel cutter 262up to the amount defined by wheel 212. The method of using keel cutterinstrument 200 is substantially identical to the method describedhereinabove with respect to keel cutter instrument 10, and thus will notbe described herein.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Any combination ofthe above embodiments is also envisioned and is within the scope of theappended claims. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of particularembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto.

What is claimed is:
 1. A surgical instrument comprising: a housingdefining a longitudinal axis; an outer shaft operatively coupled withthe housing such that rotation of the housing about the longitudinalaxis causes axial displacement of the outer shaft, the outer shaftincluding a keel cutter configured to define a channel in a vertebralbody; an inner shaft disposed within the outer shaft; a trial sizerconfigured to be received in intervertebral space, the trial sizerincluding a pair of wings transitionable between a retracted positionand an extended position in which the pair of wings extends transverselyoutward; a rod received within the inner shaft; and a head connected tothe rod, wherein the head is operatively coupled with the pair of wingssuch that axial displacement of the rod causes transition of the pair ofwings between the retracted and extended positions.
 2. The surgicalinstrument according to claim 1, wherein the trial sizer includes a pairof keel cutters.
 3. The surgical instrument according to claim 1,wherein the head includes grooves, each groove defining an acute anglewith respect to a longitudinal axis of the rod.
 4. The surgicalinstrument according to claim 3, wherein each of the wings includes aguide configured to be received in the respective groove of the head. 5.The surgical instrument of claim 4, wherein axial displacement of therod causes the guide of each of the wings to slidably move within theirrespective grooves of the head.
 6. The surgical instrument according toclaim 4, wherein the trial sizer includes pins and defines boresdimensioned to receive the respective pins, each of the wings defining alateral slot configured to slidably receive one of the pins.
 7. Thesurgical instrument according to claim 1, wherein the housing isrotatable about the outer shaft.
 8. The surgical instrument according toclaim 1, wherein the keel cutter is transitionable between an extendedposition and a retracted position, wherein the keel cutter extends overthe trial sizer when the keel cutter is in the extended position.
 9. Thesurgical instrument according to claim 1, further including a wheeloperatively coupled with the rod, wherein rotation of the wheel causesaxial displacement of the rod.
 10. The surgical instrument of claim 9,further comprising a gripping portion located distal to the wheel. 11.The surgical instrument according to claim 1, wherein the trial sizerhas a width ranging from about 14 mm to about 20 mm.
 12. The surgicalinstrument according to claim 1, wherein the trial sizer has a widthranging from about 18 mm to about 30 mm.
 13. The surgical instrumentaccording to claim 1, wherein the head is tapered.
 14. The surgicalinstrument according to claim 1, wherein the outer shaft has a pluralityof openings.
 15. The surgical instrument according to claim 1, wherein adistal-most end of the keel cutter is tapered.
 16. The surgicalinstrument according to claim 1, wherein the keel cutter extends along alongitudinal axis of the outer shaft.
 17. The surgical instrumentaccording to claim 1, wherein the keel cutter is centered between thewings.
 18. The surgical instrument of claim 1, wherein the trial sizerdefines a plane, the pair of wings extending outward along that planewhen in an extended position.
 19. A method of forming a keel channel ina vertebral body comprising: inserting a trial sizer of a keel cuttinginstrument into an intervertebral space, the trial sizer including ahousing coupled with an outer shaft, the housing defining a longitudinalaxis; axially displacing the outer shaft and a rod received within aninner shaft through rotation of the housing about the longitudinal axis;transitioning a pair of wings of the trial sizer from a retractedposition to an extended position in which the pair of wings extendstransversely outward; translating a keel cutter of the keel cuttinginstrument into a vertebral body to form a keel channel; removing thekeel cutting instrument from the intervertebral space; and placing animplant in the intervertebral space.
 20. The method according to claim19, wherein transitioning the pair of wings of the trial sizer includescentering the trial sizer within the intervertebral space.
 21. Themethod according to claim 19, further including placing the keel cutteragainst a vertebral body prior to translating the keel cutter.
 22. Themethod according to claim 19, wherein translating the keel cutterincludes rotating a housing of the keel cutting instrument rotatablycoupled with an outer shaft of the keel cutting instrument such that thekeel cutter disposed on the outer shaft extends over the trial sizer.23. The method according to claim 19, wherein placing the implant in theintervertebral space includes positioning a keel structure of theimplant into the keel channel defined in the vertebral body.
 24. Asurgical instrument comprising: a housing defining a longitudinal axis;an outer shaft operatively coupled with the housing, the outer shaftincluding a keel cutter configured to define a channel in a vertebralbody; an inner shaft disposed within the outer shaft; a trial sizerconfigured to be received in intervertebral space, the trial sizerincluding a pair of wings; a rod disposed within the inner shaft; and ahead connected to the rod, wherein, in a first state, the head is at afirst distance along the longitudinal axis and the pair of wings are ina retracted position, and, in a second state, the head is at a seconddistance along the longitudinal axis and the pair of wings are extendedtransversely outward from the trial sizer in an expanded position.